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标题: 十二条后端开发经验分享，纯干货，总有一条你不知道 [打印本页]

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作者: 守听    时间: 2022-11-30 19:45
标题: 十二条后端开发经验分享，纯干货，总有一条你不知道
前言

本文是博主从事后端开发以来，对公司、个人项目的经验总结，包含代码编写、功能推荐、第三方库使用及优雅配置等，希望大家看到都能有所收获

• 博主github地址: https://github.com/wayn111
  

一. 优雅的进行线程池异常处理

在Java开发中，线程池的使用必不可少，使用无返回值 execute() 方法时，线程执行发生异常的话，需要记录日志，方便回溯，一般做法是在线程执行方法内 try/catch 处理，如下：

1. @Test
2. public void test() throws Exception {
3.     ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 60,
4.             TimeUnit.SECONDS, new ArrayBlockingQueue<>(100000));
5.     Future<Integer> submit = threadPoolExecutor.execute(() -> {
6.         try {
7.             int i = 1 / 0;
8.             return i;
9.         } catch (Exception e) {
10.             log.error(e.getMessage(), e);
11.             return null;
12.         }
13.     });
14. }

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但是当线程池调用方法很多时，那么每个线程执行方法内都要 try/catch 处理，这就不优雅了，其实ThreadPoolExecutor类还支持传入 ThreadFactory 参数，自定义线程工厂，在创建 thread 时，指定 setUncaughtExceptionHandler 异常处理方法，这样就可以做到全局处理异常了，代码如下：

1. ThreadFactory threadFactory = r -> {
2.     Thread thread = new Thread(r);
3.     thread.setUncaughtExceptionHandler((t, e) -> {
4.         // 记录线程异常
5.         log.error(e.getMessage(), e);
6.     });
7.     return thread;
8. };
9. ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 60,
10.         TimeUnit.SECONDS, new ArrayBlockingQueue<>(100000),
11.         threadFactory);
12. threadPoolExecutor.execute(() -> {
13.     log.info("---------------------");
14.     int i = 1 / 0;
15. });

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二. 线程池决绝策略设置错误导致业务接口执行超时

先介绍下线程池得四种决绝策略

• AbortPolicy：丢弃任务并抛出RejectedExecutionException异常，这是线程池默认的拒绝策略
  
• DiscardPolicy：丢弃任务，但是不抛出异常。如果线程队列已满，则后续提交的任务都会被丢弃，且是静默丢弃。
  使用此策略，可能会使我们无法发现系统的异常状态。建议是一些无关紧要的业务采用此策略
  
• DiscardOldestPolicy：丢弃队列最前面的任务，然后重新提交被拒绝的任务。此拒绝策略，是一种喜新厌旧的拒绝策略。是否要采用此种拒绝策略，还得根据实际业务是否允许丢弃老任务来认真衡量。
  
• CallerRunsPolicy：由调用线程处理该任务
  

如下是一个线上业务接口使用得线程池配置，决绝策略采用 CallerRunsPolicy

1. // 某个线上线程池配置如下
2. ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
3.                 50, // 最小核心线程数
4.                 50, // 最大线程数，当队列满时，能创建的最大线程数
5.                 60L, TimeUnit.SECONDS, // 空闲线程超过核心线程时，回收该线程的最大等待时间
6.                 new LinkedBlockingQueue<>(5000), // 阻塞队列大小,当核心线程使用满时，新的线程会放进队列
7.             new CustomizableThreadFactory("task"), // 自定义线程名
8.                 new ThreadPoolExecutor.CallerRunsPolicy() // 线程执行的拒绝策略
9.         );

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在某些情况下，子线程任务调用第三方接口超时，导致核心线程数、最大线程数占满、阻塞队列占满的情况下执行拒绝策略时，由于使用 CallerRunsPolicy 策略，导致业务线程执行子任务时继续超时，进而导致接口执行异常，这种情况下，考虑到子线程任务得重要性，不是很重要得话，可以使用 DiscardPolicy 策略，要是很重要，可以发送到消息队列中持久化子线程任务数据待后续处理
三. 优雅的单例模式懒加载帮助类代码实现

博主推荐通过静态内部类实现单例模式，并实现懒加载效果，代码如下

1. // 使用静态内部类完成单例模式封装，避免线程安全问题，避免重复初始化成员属性  
2. @Slf4j  
3. public class FilterIpUtil {  
4.   
5.     private FilterIpUtil() {  
6.     }  
7.   
8.     private List<String> strings = new ArrayList<>();  
9.   
10.     // 代码块在FilterIpUtil实例初始化时才会执行  
11.     {  
12.    
13.         // 在代码块中完成文件的第一次读写操作，后续不再读这个文件
14.         System.out.println("FilterIpUtil init");  
15.         try (InputStream resourceAsStream = FilterIpUtil.class.getClassLoader().getResourceAsStream("filterIp.txt")) {  
16.             // 将文件内容放到string集合中  
17.             IoUtil.readUtf8Lines(resourceAsStream, strings);  
18.         } catch (IOException e) {  
19.             log.error(e.getMessage(), e);  
20.         }  
21.     }  
22.   
23.     public static FilterIpUtil getInstance() {  
24.         return InnerClassInstance.instance;  
25.     }  
26.     // 使用内部类完成单例模式，由jvm保证线程安全  
27.     private static class InnerClassInstance {  
28.         private static final FilterIpUtil instance = new FilterIpUtil();  
29.     }  
30.   
31.     // 判断集合中是否包含目标参数  
32.     public boolean isFilter(String arg) {  
33.         return strings.contains(arg);  
34.     }  
35.   
36. }

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四. 使用ip2region实现请求地址解析

在博主之前公司得项目中，ip解析是调用淘宝IP还有聚合IP接口获取结果，通常耗时200毫秒左右，并且接口不稳定时而会挂。都会影响业务接口耗时，后来在 github 上了解到 ip2region 这个项目，使用本地ip库查询，查询速度微秒级别， 精准度能达到90%，但是ip库还是有少部分ip信息不准，建议数据库中把请求ip地址保存下来。简介如下：
ip2region v2.0 - 是一个离线IP地址定位库和IP定位数据管理框架，10微秒级别的查询效率，提供了众多主流编程语言的 xdb 数据生成和查询客户端实现基于 xdb 文件的查询，下面是一个 Spring 项目中 ip2region 帮助类来实现ip地址解析

1. /**
2. * ip2region工具类
3. */
4. @Slf4j
5. @Component
6. public class Ip2region {
8.     private Searcher searcher = null;
10.     @Value("${ip2region.path:}")
11.     private String ip2regionPath = "";
13.     @PostConstruct
14.     private void init() {
15.         // 1、从 dbPath 加载整个 xdb 到内存。
16.         String dbPath = ip2regionPath;
18.         // 1、从 dbPath 加载整个 xdb 到内存。
19.         byte[] cBuff;
20.         try {
21.             cBuff = Searcher.loadContentFromFile(dbPath);
22.             searcher = Searcher.newWithBuffer(cBuff);
23.         } catch (Exception e) {
24.             log.error("failed to create content cached searcher: {}", e.getMessage(), e);
25.         }
26.     }
28.     public IpInfoBean getIpInfo(String ip) {
29.         if (StringUtils.isBlank(ip)) {
30.             return null;
31.         }
33.         // 3、查询
34.         try {
35.             long sTime = System.nanoTime();
36.             // 国家|区域|省份|城市|ISP
37.             String region = searcher.search(ip);
38.             long cost = TimeUnit.NANOSECONDS.toMicros((long) (System.nanoTime() - sTime));
39.             log.info("{region: {}, ioCount: {}, took: {} μs}", region, searcher.getIOCount(), cost);
40.             if (StringUtils.isNotBlank(region)) {
41.                 String[] split = region.split("\|");
42.                 IpInfoBean ipInfo = new IpInfoBean();
43.                 ipInfo.setIp(ip);
44.                 if (!"".equals(split[0])) {
45.                     ipInfo.setCountry(split[0]);
46.                 }
47.                 if (!"".equals(split[2])) {
48.                     ipInfo.setProvince(split[2]);
49.                 }
50.                 if (!"".equals(split[3])) {
51.                     ipInfo.setCity(split[3]);
52.                 }
53.                 if (!"".equals(split[4])) {
54.                     ipInfo.setIsp(split[4]);
55.                 }
56.                 return ipInfo;
57.             }
58.         } catch (Exception e) {
59.             log.error("failed to search({}): {}", ip, e);
60.             return null;
61.         }
63.         // 4、关闭资源 - 该 searcher 对象可以安全用于并发，等整个服务关闭的时候再关闭 searcher
64.         // searcher.close();
66.         // 备注：并发使用，用整个 xdb 数据缓存创建的查询对象可以安全的用于并发，也就是你可以把这个 searcher 对象做成全局对象去跨线程访问。
67.         return null;
68.     }
69. }

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要注意得就是 ip2region v2.0 版本使用的xdb文件不建议放在项目 resources 下一起打包，存在编码格式问题，建议通过指定路径加载得方式单独放在服务器目录下
五. 优雅得Springboot + mybatis配置多数据源方式

Springboot + mybatis 得项目中一般通过 @MapperScan 注解配置 dao 层包目录，来实现 dao 层增强，其实项目中配置一个@MapperScan 是指定一个数据源，配置两个@MapperScan就可以指定两个数据源，通过不同得 dao 层包目录区分，来实现不同数据源得访问隔离。
比如下面代码中，com.xxx.dao.master 目录下为主数据源 dao 文件，com.xxx.dao.slave 为从数据源 dao 文件，这个方式比网上得基于 aop 加注解得方式更加简洁好用，也没有单个方法中使用不同数据源切换得问题，因此推荐这种写法

1. /**
2. * 主数据源
3. */
4. @Slf4j
5. @Configuration
6. @MapperScan(basePackages = {"com.xxx.dao.master"},
7.         sqlSessionFactoryRef = "MasterSqlSessionFactory")
8. public class MasterDataSourceConfig {
10.     @Bean(name = "MasterDataSource")
11.     @Qualifier("MasterDataSource")
12.     @ConfigurationProperties(prefix = "spring.datasource.master")
13.     public DataSource clickHouseDataSource() {
14.         return DruidDataSourceBuilder.create().build();
15.     }
17.     @Bean(name = "MasterSqlSessionFactory")
18.     public SqlSessionFactory getSqlSessionFactory(@Qualifier("MasterDataSource") DataSource dataSource) throws Exception {
19.         MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
20.         sessionFactoryBean.setDataSource(dataSource);
21.         sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
22.                 .getResources("classpath*:mapper/master/*.xml"));
23.         log.info("------------------------------------------MasterDataSource 配置成功");
24.         return sessionFactoryBean.getObject();
25.     }
26. }
28. /**
29. * 从数据源
30. */
31. @Slf4j
32. @Configuration
33. @MapperScan(basePackages = {"com.xxx.dao.slave"},
34.         sqlSessionFactoryRef = "SlaveSqlSessionFactory")
35. public class MasterDataSourceConfig {
37.     @Bean(name = "SlaveDataSource")
38.     @Qualifier("SlaveDataSource")
39.     @ConfigurationProperties(prefix = "spring.datasource.slave")
40.     public DataSource clickHouseDataSource() {
41.         return DruidDataSourceBuilder.create().build();
42.     }
44.     @Bean(name = "SlaveSqlSessionFactory")
45.     public SqlSessionFactory getSqlSessionFactory(@Qualifier("SlaveDataSource") DataSource dataSource) throws Exception {
46.         MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
47.         sessionFactoryBean.setDataSource(dataSource);
48.         sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
49.                 .getResources("classpath*:mapper/slave/*.xml"));
50.         log.info("------------------------------------------SlaveDataSource 配置成功");
51.         return sessionFactoryBean.getObject();
52.     }
53. }

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数据源yml配置

1. spring:
2.   datasource:
3.     type: com.alibaba.druid.pool.DruidDataSource
4.     driverClassName: com.mysql.cj.jdbc.Driver
5.     # 主库数据源
6.     master:
7.       url: jdbc:mysql://localhost:3306/db1?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
8.       username: root
9.       password:
10.     slave:
11.       url: jdbc:mysql://localhost:3306/db2?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
12.       username: root
13.       password:

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博主刚开始编码一、两年得时候一个项目中遇到了多数据源使用得问题，那时候题主便在网上搜索Spring 多数据源得帖子，大多数都是基于Spring提供得AbstractRoutingDataSource + AOP + 注解 来做动态切换，包括现在流行得 Mybatis plus 官方得多数据源解决方案也是这种做法，这种做法解决了博主当时得多数据源使用问题，后来加了一个需求，在一个定时任务中，查询两个数据源得数据，才发现动态切换在单个方法中不好用了，最后使用得原生jdbc数据源解决。多年后，博主在另一家公司得项目中又遇到了多数据源问题，但是这次博主在网上搜索得是Mybatis 多数据源，才发现了这个优雅得解决方案，进而推荐给大家
六. Spring Security项目中，使用MDC实现接口请求调用追踪，以及用户ID记录

MDC介绍

MDC(Mapped Diagnostic Context，映射调试上下文)是 log4j 、logback及log4j2 提供的一种方便在多线程条件下记录日志的功能。MDC 可以看成是一个与当前线程绑定的哈希表，可以往其中添加键值对。MDC 中包含的内容可以被同一线程中执行的代码所访问。当前线程的子线程会继承其父线程中的 MDC 的内容。当需要记录日志时，只需要从 MDC 中获取所需的信息即可。
虽然MDC能够方便得实现接口请求调用追踪功能，但是它在子线程中会丢失父线程中添加得键值对信息，解决方法是通过父线程中调用线程池前调用 MDC.getCopyOfContextMap() ，然后在子线程中第一个调用  MDC.setConextMap() 获取键值对信息，完整实现代码如下：

1. /**
2. * 自定义Spring线程池，解决子线程丢失reqest_id问题
3. */
4. public class ThreadPoolExecutorMdcWrapper extends ThreadPoolTaskExecutor {
6.     @Override
7.     public void execute(Runnable task) {
8.         super.execute(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
9.     }
11.     @Override
12.     public <T> Future<T> submit(Callable<T> task) {
13.         return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
14.     }
16.     @Override
17.     public Future<?> submit(Runnable task) {
18.         return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
19.     }
20. }
22. /**
23. * MDC帮助类，添加reqest_id
24. */
25. public class ThreadMdcUtil {
28.     public static final String REQUEST_ID = "request_id";
30.     /**
31.      * 设置请求唯一ID
32.      */
33.     public static void setTraceIdIfAbsent() {
34.         if (MDC.get(REQUEST_ID) == null) {
35.             MDC.put(REQUEST_ID, IdUtil.getUid());
36.         }
37.     }
39.     /**
40.      * 存在userId则添加到REQUEST_ID中
41.      * @param userId
42.      */
43.     public static void setUserId(String userId) {
44.         String s = MDC.get(REQUEST_ID);
45.         if (s != null) {
46.             MDC.put(REQUEST_ID, s + "_" + userId);
47.         }
48.     }
50.     public static void removeTraceId() {
51.         MDC.remove(REQUEST_ID);
52.     }
54.     public static <T> Callable<T> wrap(final Callable<T> callable, final Map<String, String> context) {
55.         return () -> {
56.             if (context == null) {
57.                 MDC.clear();
58.             } else {
59.                 MDC.setContextMap(context);
60.             }
61.             setTraceIdIfAbsent();
62.             try {
63.                 return callable.call();
64.             } finally {
65.                 MDC.clear();
66.             }
67.         };
68.     }
70.     public static Runnable wrap(final Runnable runnable, final Map<String, String> context) {
71.         return () -> {
72.             if (context == null) {
73.                 MDC.clear();
74.             } else {
75.                 MDC.setContextMap(context);
76.             }
77.             // 设置traceId
78.             setTraceIdIfAbsent();
79.             try {
80.                 runnable.run();
81.             } finally {
82.                 MDC.clear();
83.             }
84.         };
85.     }
86. }

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在 Spring Security 中添加 token 过滤器

1. /**
2. * token过滤器 验证token有效性
3. *
4. * @author ruoyi
5. */
6. @Slf4j
7. @Component
8. public class JwtAuthenticationTokenFilter extends OncePerRequestFilter {
10.     @Autowired
11.     private TokenService tokenService;
14.     @Override
15.     protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
16.             throws ServletException, IOException {
17.         try {
18.             // 入口传入请求ID
19.             ThreadMdcUtil.setTraceIdIfAbsent();
20.             LoginUserDetail loginUser = tokenService.getLoginUser(request);
21.             if (Objects.nonNull(loginUser) && Objects.isNull(SecurityContextHolder.getContext().getAuthentication())) {
22.                 // 记录userId
23.                 ThreadMdcUtil.setUserId(String.valueOf(loginUser.getMember().getId()));
24.                 tokenService.verifyToken(loginUser);
25.                 UsernamePasswordAuthenticationToken authenticationToken = new UsernamePasswordAuthenticationToken(loginUser, null, loginUser.getAuthorities());
26.                 authenticationToken.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
27.                 SecurityContextHolder.getContext().setAuthentication(authenticationToken);
28.             }
29.             chain.doFilter(request, response);
30.         } finally {
31.             // 出口移除请求ID
32.             ThreadMdcUtil.removeTraceId();
33.         }
34.     }
36. }

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最后在 logback.xml 中添加 %X{request_id}

1. [/code]日志打印效果如下：
2. [code]2022-11-27 21:29:48.008 [86c76336100c414dbe9217aeb099ccd5_12] [http-nio-82-exec-2] [INFO ] c.w.m.a.s.impl.IHomeServiceImpl:56 getHomeIndexDataCompletableFuture - getHomeIndexDataCompletableFuture:com.wayn.common.util.R@701f7b8e[code=200,msg=操作成功,map={bannerList=[{"createTime":"2020-06-26 19:56:03","delFlag":false,"id":14,"imgUrl":"https://m.360buyimg.com/mobilecms/s700x280_jfs/t1/117335/39/13837/263099/5f291a83E8ba761d0/5c0460445cb28248.jpg!cr_1125x449_0_166!q70.jpg.dpg","jumpUrl":"http://82.157.141.70/mall/#/detail/1155015","sort":0,"status":0,"title":"hh2","updateTime":"2022-06-19 09:16:46"},{"createTime":"2020-06-26 19:56:03","delFlag":false,"id":15,"imgUrl":"https://m.360buyimg.com/mobilecms/s700x280_jfs/t1/202096/26/11652/265782/616acb67E4fcdc9ac/8d7cdfbb6c934e67.jpg!cr_1125x449_0_166!q70.jpg.dpg","jumpUrl":"#/detail/1155015","sort":0,"status":0,"title":"hh","updateTime":"2022-06-19 09:04:58"}], newGoodsList=[{"actualSales":0,"brandId":0,"brief":"酥脆奶香，甜酸回味","categoryId":1008015,"counterPrice":56.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1116011","id":1116011,"isHot":true,"isNew":true,"isOnSale":true,"keywords":"","name":"蔓越莓曲奇 200克","picUrl":"http://yanxuan.nosdn.127.net/767b370d07f3973500db54900bcbd2a7.png","retailPrice":36.00,"shareUrl":"","sort":5,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"粉彩色泽，记录生活","categoryId":1012003,"counterPrice":49.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1127047","id":1127047,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"趣味粉彩系列笔记本","picUrl":"http://yanxuan.nosdn.127.net/6c03ca93d8fe404faa266ea86f3f1e43.png","retailPrice":29.00,"shareUrl":"","sort":2,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"慢回弹海绵，时尚设计。","categoryId":1008002,"counterPrice":66.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1134030","id":1134030,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"简约知性记忆棉坐垫","picUrl":"http://yanxuan.nosdn.127.net/aa49dfe878becf768eddc4c1636643a6.png","retailPrice":46.00,"shareUrl":"","sort":12,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"慢回弹海绵的呵护，萌趣添彩。","categoryId":1008002,"counterPrice":69.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1134032","id":1134032,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"趣味粉彩系列记忆棉坐垫","picUrl":"http://yanxuan.nosdn.127.net/8b30eeb17c831eba08b97bdcb4c46a8e.png","retailPrice":49.00,"shareUrl":"","sort":13,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"100%桑蚕丝，丝滑润肤","categoryId":1008009,"counterPrice":2619.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1135002","id":1135002,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"宫廷奢华真丝四件套","picUrl":"http://yanxuan.nosdn.127.net/45548f26cfd0c7c41e0afc3709d48286.png","retailPrice":2599.00,"shareUrl":"","sort":1,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"自由海军领探索未来梦","categoryId":1020003,"counterPrice":89.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1135072","id":1135072,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"经典海魂纹水手裙（婴童）","picUrl":"http://yanxuan.nosdn.127.net/43e57d4208cdc78ac9c088f9b3e798f5.png","retailPrice":69.00,"shareUrl":"","sort":3,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"经典海魂纹自由海军领","categoryId":1020003,"counterPrice":89.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1135073","id":1135073,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"海魂纹哈衣水手服（婴童）","picUrl":"http://yanxuan.nosdn.127.net/53052b04ae001d289c040e09ea92231c.png","retailPrice":69.00,"shareUrl":"","sort":4,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":5,"brandId":0,"brief":"差旅好伴侣","categoryId":1032000,"counterPrice":119.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1152031","id":1152031,"isHot":true,"isNew":true,"isOnSale":true,"keywords":"","name":"魔兽世界-伊利丹颈枕眼罩套装","picUrl":"http://yanxuan.nosdn.127.net/fd6e78a397bd9e9804116a36f0270b0a.png","retailPrice":99.00,"shareUrl":"","sort":4,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":5,"brandId":0,"brief":"桌面整理神器","categoryId":1032000,"counterPrice":519.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1152095","id":1152095,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"魔兽世界 联盟·暴风城 堡垒收纳盒","picUrl":"http://yanxuan.nosdn.127.net/c86b49f635fa141decebabbd0966a6ef.png","retailPrice":499.00,"shareUrl":"","sort":6,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"3重透气，清爽柔滑","categoryId":1008009,"counterPrice":479.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1152161","id":1152161,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"竹语丝麻印花四件套","picUrl":"http://yanxuan.nosdn.127.net/977401e75113f7c8334c4fb5b4bf6215.png","retailPrice":459.00,"shareUrl":"","sort":6,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10}], categoryList=[{"createTime":"2020-12-08 23:09:12","delFlag":false,"iconUrl":"http://cdn.wayn.xin/9fc3c52571aa38a1466f114c2dc892fc.png","id":2,"jumpType":0,"name":"大牌手机","picUrl":"http://cdn.wayn.xin/2545dd00ca4575759024af2811949a9d.jpg","sort":1,"status":0,"updateTime":"2020-12-12 19:26:48","valueId":5,"valueUrl":"http://baidu.com"},{"createTime":"2020-12-06 13:27:54","delFlag":false,"iconUrl":"http://82.157.141.70/upload/2022/02/21/a23fa32c8f4004a8c9fbbb1784462163.jpg","id":1,"jumpType":0,"name":"滋补保健2","picUrl":"http://cdn.wayn.xin/d4de7172eb7ae4178ae4dafd6a973d8f.jpg","sort":2,"status":0,"updateTime":"2022-06-19 09:17:20","valueId":2},{"createTime":"2020-12-08 23:26:15","delFlag":false,"iconUrl":"http://cdn.wayn.xin/6bc0f8a131d2d16b8fc2004d4aa4860c.png","id":3,"jumpType":1,"name":"不锈钢锅","picUrl":"http://cdn.wayn.xin/314d87257f7a2ff03d5f4c5183797912.jpg","sort":2,"status":0,"updateTime":"2020-12-12 19:27:24","valueId":1036000},{"createTime":"2020-12-12 19:28:08","delFlag":false,"iconUrl":"http://cdn.wayn.xin/5a90531d901529967885279d7dc826e1.png","id":14,"jumpType":0,"name":"进口牛奶","picUrl":"http://cdn.wayn.xin/0b1f6ab63d5e222c52c83a2d0581e44c.jpg","sort":3,"status":0,"valueId":5},{"createTime":"2020-12-12 19:28:33","delFlag":false,"iconUrl":"http://cdn.wayn.xin/33530951827ca7e59940d51cda537d84.png","id":15,"jumpType":0,"name":"量贩囤货","picUrl":"http://cdn.wayn.xin/bb6daee3b3e51c3008db97585249f513.jpg","sort":4,"status":0,"valueId":2},{"createTime":"2020-12-12 19:28:50","delFlag":false,"iconUrl":"http://cdn.wayn.xin/7d337f25111b263b29d5d12589015c46.png","id":16,"jumpType":0,"name":"清洁用品","picUrl":"http://cdn.wayn.xin/be8995bda39d03b17349b8ec0dcab3d5.jpg","sort":5,"status":0,"valueId":2},{"createTime":"2020-12-12 19:29:10","delFlag":false,"iconUrl":"http://cdn.wayn.xin/2e632ec0173bb477dcdb601495e0412a.png","id":17,"jumpType":0,"name":"洗护用品","picUrl":"http://cdn.wayn.xin/53fb88c9d1245caa882aa3fc29187d0b.jpg","sort":6,"status":0,"valueId":4},{"createTime":"2020-12-12 19:29:28","delFlag":false,"iconUrl":"http://cdn.wayn.xin/942323c0e74677cf2aa15f09a1e63bca.png","id":18,"jumpType":0,"name":"日用百货","picUrl":"http://cdn.wayn.xin/8587f91db2edcb43e57da9835cc7ec76.jpg","sort":7,"status":0,"valueId":2},{"createTime":"2020-12-12 19:29:46","delFlag":false,"iconUrl":"http://cdn.wayn.xin/18d9d860ba9b8b28522e050f11a8a8e0.png","id":19,"jumpType":0,"name":"明星乳胶","picUrl":"http://cdn.wayn.xin/65273c7fb2273e90958e92626248a90a.jpg","sort":8,"status":0,"valueId":6},{"createTime":"2020-12-12 19:30:15","delFlag":false,"iconUrl":"http://cdn.wayn.xin/7c790577afda91eebc3c95586e190957.png","id":20,"jumpType":0,"name":"口碑好物","picUrl":"http://cdn.wayn.xin/210011b35be4ceee39e6a466b40b8e22.jpg","sort":9,"status":0,"updateTime":"2021-04-01 20:13:08","valueId":5}], expire_time=1669549170235, hotGoodsList=[{"actualSales":1,"brandId":1001045,"brief":"一级桑蚕丝，吸湿透气柔软","categoryId":1036000,"counterPrice":719.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1006013","id":1006013,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"双宫茧桑蚕丝被 空调被","picUrl":"http://yanxuan.nosdn.127.net/583812520c68ca7995b6fac4c67ae2c7.png","retailPrice":699.00,"shareUrl":"","sort":7,"unit":"件","updateTime":"2021-08-08 11:19:36","virtualSales":10},{"actualSales":1,"brandId":1001045,"brief":"双层子母被，四季皆可使用","categoryId":1008008,"counterPrice":14199.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1006014","id":1006014,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"双宫茧桑蚕丝被 子母被","picUrl":"http://yanxuan.nosdn.127.net/2b537159f0f789034bf8c4b339c43750.png","retailPrice":1399.00,"shareUrl":"","sort":15,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":1001000,"brief":"加大加厚，双色精彩","categoryId":1036000,"counterPrice":219.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1011004","id":1011004,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"色织精梳AB纱格纹空调被","picUrl":"http://yanxuan.nosdn.127.net/0984c9388a2c3fd2335779da904be393.png","retailPrice":199.00,"shareUrl":"","sort":2,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":0,"brief":"共享亲密2人时光","categoryId":1008008,"counterPrice":219.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1019002","id":1019002,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"升级款护颈双人记忆枕","picUrl":"http://yanxuan.nosdn.127.net/0118039f7cda342651595d994ed09567.png","retailPrice":199.00,"shareUrl":"","sort":10,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":0,"brief":"健康保护枕","categoryId":1008008,"counterPrice":119.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1019006","id":1019006,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"植物填充护颈夜交藤枕","picUrl":"http://yanxuan.nosdn.127.net/60c3707837c97a21715ecc3986a744ce.png","retailPrice":99.00,"shareUrl":"","sort":7,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":0,"brief":"厚实舒适","categoryId":1008001,"counterPrice":59.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1021000","id":1021000,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"被","name":"埃及进口长绒棉毛巾","picUrl":"http://yanxuan.nosdn.127.net/7191f2599c7fe44ed4cff7a76e853154.png","retailPrice":39.00,"shareUrl":"","sort":7,"unit":"条","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":1001020,"brief":"浪漫毛线绣球，简约而不简单","categoryId":1008009,"counterPrice":319.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1022000","id":1022000,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"意式毛线绣球四件套","picUrl":"http://yanxuan.nosdn.127.net/5350e35e6f22165f38928f3c2c52ac57.png","retailPrice":299.00,"shareUrl":"","sort":18,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":32,"brandId":1001000,"brief":"柔软纱布，婴童可用","categoryId":1036000,"counterPrice":269.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1027004","id":1027004,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"色织六层纱布夏凉被","picUrl":"http://yanxuan.nosdn.127.net/6252f53aaf36c072b6678f3d8c635132.png","retailPrice":249.00,"shareUrl":"","sort":3,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":32,"brandId":0,"brief":"原生苦荞，健康护颈","categoryId":1008008,"counterPrice":119.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1036002","id":1036002,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"高山苦荞麦枕","picUrl":"http://yanxuan.nosdn.127.net/ffd7efe9d5225dff9f36d5110b027caa.png","retailPrice":99.00,"shareUrl":"","sort":5,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":32,"brandId":0,"brief":"5cm记忆绵的亲密包裹","categoryId":1008008,"counterPrice":619.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1037011","id":1037011,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"安睡慢回弹记忆绵床垫","picUrl":"http://yanxuan.nosdn.127.net/a03ea6f4509439acdafcb7ceba1debe0.png","retailPrice":599.00,"shareUrl":"","sort":22,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10}]}]
3. 2022-11-27 21:29:48.336 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage_mpCount:137 debug - ==>  Preparing: SELECT COUNT(*) AS total FROM shop_goods WHERE del_flag = 0 AND is_on_sale = 1
4. 2022-11-27 21:29:48.387 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage_mpCount:137 debug - ==> Parameters:
5. 2022-11-27 21:29:48.426 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage_mpCount:137 debug - <==      Total: 1
6. 2022-11-27 21:29:48.430 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage:137 debug - ==>  Preparing: select id, goods_sn, name, pic_url, counter_price, retail_price, actual_sales, virtual_sales from shop_goods WHERE del_flag = 0 and is_on_sale = 1 order by create_time desc LIMIT ?
7. 2022-11-27 21:29:48.452 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage:137 debug - ==> Parameters: 6(Long)
8. 2022-11-27 21:29:48.476 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage:137 debug - <==      Total: 6

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在以上代码中，打个比方想要实现性别字段得自定义格式转换，就需要在convertToExcelData方法中，添加如下代码

1. public class CustomStringStringConverter implements Converter<String> {
2.     @Override
3.     public Class<?> supportJavaTypeKey() {
4.         return String.class;
5.     }
7.     @Override
8.     public CellDataTypeEnum supportExcelTypeKey() {
9.         return CellDataTypeEnum.STRING;
10.     }
12.     /**
13.      * 这里读的时候会调用
14.      *
15.      * @param context
16.      * @return
17.      */
18.     @Override
19.     public String convertToJavaData(ReadConverterContext<?> context) {
20.         return "自定义：" + context.getReadCellData().getStringValue();
21.     }
23.     /**
24.      * 这里是写的时候会调用 不用管
25.      *
26.      * @return
27.      */
28.     @Override
29.     public WriteCellData<?> convertToExcelData(WriteConverterContext<String> context) {
30.         return new WriteCellData<>(context.getValue());
31.     }
33. }

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可以看到，非常得不优雅，对于这种类型字段，博主习惯使用枚举类来定义字段所有类型，然后将枚举类转换为 map(value,desc) 结构，就可以优雅得实现这个自定义格式得需求

1. @Override
2. public WriteCellData<?> convertToExcelData(WriteConverterContext<String> context) {
3.     String value = context.getValue();
4.     if ("man".equals(value)) {
5.         return new WriteCellData<>("男");
6.     } else {
7.         return new WriteCellData<>("女");
8.     }
9. }

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最后再导出 ExcelProperty 中甜腻加 StatusConverter ，就优雅得实现了自定义格式得需求

1. /**
2. * 一、先定义int字段抽象转换类，实现通用转换逻辑
3. */
4. public abstract class AbstractIntConverter implements Converter<Integer> {
5.     abstract List<ConverterDTO> getArr();
7.     public WriteCellData<?> convertToExcelData(Integer value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) {
8.         List<ConverterDTO> values = getArr();
9.         Map<Integer, String> map = values.stream().collect(toMap(ConverterDTO::getType, ConverterDTO::getDesc));
10.         String result = map.getOrDefault(value, "");
11.         return new WriteCellData<>(result);
12.     }
14.     static class ConverterDTO {
15.         private Integer type;
16.         private String desc;
18.         public Integer getType() {
19.             return type;
20.         }
22.         public void setType(Integer type) {
23.             this.type = type;
24.         }
26.         public String getDesc() {
27.             return desc;
28.         }
30.         public void setDesc(String desc) {
31.             this.desc = desc;
32.         }
34.         public ConverterDTO(Integer type, String desc) {
35.             this.type = type;
36.             this.desc = desc;
37.         }
38.     }
39. }
41. /**
42. * 二、定义通用状态字段转换类
43. */
44. public class StatusConverter extends AbstractIntConverter {
46.     @Override
47.     List<ConverterDTO> getArr() {
48.         StatusEnum[] values = StatusEnum.values();
49.         return Arrays.stream(values).map(sexEnum -> new ConverterDTO(sexEnum.getType(), sexEnum.getDesc())).toList();
50.     }
52.     /**
53.      * 状态枚举
54.      */
55.     enum StatusEnum {
56.         MAN(0, "启用"),
57.         WOMAN(1, "禁用");
59.         private Integer type;
60.         private String desc;
62.         StatusEnum(Integer type, String desc) {
63.             this.type = type;
64.             this.desc = desc;
65.         }
66.         public Integer getType() {
67.             return type;
68.         }
69.         public String getDesc() {
70.             return desc;
71.         }
72.     }
73. }

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八. Springboot 默认redis客户端lettuce经常连接超时解决方案

不知道大家有没有遇到这种情况，线上项目使用 lettuce 客户端，当操作 redis 得接口一段时间没有调用后（比如30分钟），再次调用 redis 操作后，就会遇到连接超时得问题，导致接口异常。博主直接给出分析过程：

• 通过wireshark抓包工具，发现项目中 redis 连接创建后，一段时间未传输数据后，客户端发送 psh 包，未收到服务端 ack 包，触发tcp得超时重传机制，在重传次数重试完后，最终客户端主动关闭了连接。
  

到这里我们就知道这个问题，主要原因在于服务端没有回复客户端（比如tcp参数设置、防火墙主动关闭等，都是针对一段时间内没有数据传输得tcp连接会做关闭处理），造成了客户端得连接超时
面对这个问题有三种解决方案：

• redis操作异常后进行重试，这篇文章有介绍 生产环境Redis连接，长时间无响应被服务器断开问题
  
• 启用一个心跳定时任务，定时访问 redis，保持 redis 连接不被关闭，简而言之，就是写一个定时任务，定时调用 redis得 get 命令，进而保活 redis 连接
  
• 基于Springboot 提供得 LettuceClientConfigurationBuilderCustomizer 自定义客户端配置，博主这里主要针对第三种自定义客户端配置来讲解一种优雅得方式
  

Springboot 项目中关于 lettuce 客户端得自动配置是没有启用保活配置得，要启用得话代码如下：

1. public class User extends BaseEntity {
2.     ...
3.     /**
4.      * 用户状态 0 启用 1 禁用
5.      */
6.     @ExcelProperty(value = "用户状态", converter = StatusConverter.class)
7.     private Integer userStatus;
8.     ...
10. }

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添加 lettuce 客户端的自定义配置，在 KeepAliveOptions 中启用 enable ，这样 lettuce 客户端就会在tcp协议规范上启用 keep alive 机制自动发送心跳包
九. redis客户端lettuce启用epoll

直接给 官网连接，配置很简单，添加一个 netty-all 得依赖，lettuce 会自动检测项目系统是否支持 epoll（linux 系统支持），并且是否有netty-transport-native-epoll依赖（ netty-all 包含 netty-transport-native-epoll ），都满足得话就会自动启用 epoll 事件循环，进一步提升系统性能

1. /**
2. * 自定义lettuce客户端配置
3. *
4. * @return LettuceClientConfigurationBuilderCustomizer
5. */
6. @Bean
7. public LettuceClientConfigurationBuilderCustomizer lettuceClientConfigurationBuilderCustomizer() {
8.     return clientConfigurationBuilder -> {
9.         LettuceClientConfiguration clientConfiguration = clientConfigurationBuilder.build();
10.         ClientOptions clientOptions = clientConfiguration.getClientOptions().orElseGet(ClientOptions::create);
11.         ClientOptions build = clientOptions.mutate().build();
12.         SocketOptions.KeepAliveOptions.Builder builder = build.getSocketOptions().getKeepAlive().mutate();
13.         // 保活配置
14.         builder.enable(true);
15.         builder.idle(Duration.ofSeconds(30));
16.         SocketOptions.Builder socketOptionsBuilder = clientOptions.getSocketOptions().mutate();
17.         SocketOptions.KeepAliveOptions keepAliveOptions = builder.build();
18.         socketOptionsBuilder.keepAlive(keepAliveOptions);
19.         SocketOptions socketOptions = socketOptionsBuilder.build();
20.         ClientOptions clientOptions1 = ClientOptions.builder().socketOptions(socketOptions).build();
21.         clientConfigurationBuilder.clientOptions(clientOptions1);
22.     };
23. }

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十. Springboot web项目优雅停机

web项目配置了优雅停机后，在重启jar包，或者容器时可以防止正在活动得线程被突然停止（ kill -9 无解，请不要使用这个参数杀线上进程，docker compose 项目尽量不要用 docker-compose down 命令关闭项目，使用 docker-compose rm -svf 可以触发优雅停机），造成用户请求失败，在此期间允许完成现有请求但不允许新请求，配置如下：

1. <dependency>
2.     <groupId>io.netty</groupId>
3.     <artifactId>netty-all</artifactId>
4. </dependency>

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十一. nginx配置通用请求后缀

先说下这个配置产生得前提，博主公司pc客户项目是基于 electron 打包得网页项目，每次项目大版本更新时，为了做好兼容性，防止客户端网页缓存等，会使用一个新网页地址，打个比方：
老网页地址，v1.1.0 版本网页访问地址：http://api.dev.com/pageV110
新网页地址，v1.2.0 版本网页访问地址：http://api.dev.com/pageV120
那么项目得nginx配置则则需要新加一个 v1.2.0 得配置如下：

1. server: shutdown: "graceful"

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那么博主在每次项目发布得时候就需要配合前端发版，配置一个新网页，故产生了这个通用配置得需求，如下：

1. server {
2.    listen 80;
3.    server_name api.dev.com;
4.    client_max_body_size 10m;
6.    # 老网页v1.1.0配置
7.    location ~ ^/pageV110 {
8.                alias  /home/wwwroot/api.dev.com/pageV110;
9.                index  index.html index.htm;
10.        }
11.       
12.    # 新网页v1.2.0配置
13.    location ~ ^/pageV120 {
14.                alias  /home/wwwroot/api.dev.com/pageV120;
15.                index  index.html index.htm;
16.        }
18. }

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在 nginx 配置文件语法中，location 语句可以使用正则表达式，定义 set $s $1 变量，实现了通用配置
十二. 关于开发人员的自我提升和突破

博主这里主要总结了四点：

• 多和他人沟通，沟通能把复杂问题简单化，有时候开发阶段一个需求多问几句，可以减少因为个人理解差异导致的需求不一致问题，进而减少开发时间
  
• 建立长短期目标，观看技术视频、书籍给自己充电，比如7天利用业余时间看完一本电子书，三十天从零开始一个新项目等
  
• 善于总结，对于项目中的疑难bug，踩坑点要有记录，防止下次遇到再掉坑里
  
• 敢于尝试、担责，对项目、代码里明确不合理的地方要敢于跟他人沟通，修改问题代码，达到优化目的。对于自己造成的问题要承担，不要推卸责任。对于线上问题要重视，优先解决线上问题。
  

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